“Diplodocus would most likely have fed predominantly on leaves,
either biting them off -- much like how we use our incisors -- or
raking their teeth along a branch, shearing leaves off the
branch,” lead author Mark Young told Discovery News.

Co-author Paul Barrett added, “It's likely that Diplodocus fed
most often on conifer leaves (and accidentally ingested small
twigs and branches) and also on ferns and horsetails.”

Young, a researcher in the University of Edinburgh’s School of
GeoSciences, and his team made those determinations after
creating a 3D model of a complete Diplodocus skull using data
from a CT scan. The model was then biomechanically analyzed using
a technique called finite element analysis (FEA) to test common
feeding behaviors.

FEA is widely implemented to do everything from designing
airplanes to making orthopedic implants. It revealed the various
stresses and strains acting on the Diplodocus skull during
feeding to determine whether the skull or teeth would break under
certain conditions.

“Using these techniques, borrowed from the worlds of engineering
and medicine, we can start to examine the feeding behavior of
this long-extinct animal in levels of detail that were simply
impossible until recently,” Barrett, a paleontologist at the
Natural History Museum in London, said.

The research shows that the skull and teeth of the toothy, iconic
looking dinosaur were biomechanically suitable for biting off
leaves, raking through branches, and breaking off leaves. The
dinosaur did not rip bark from trees, as some living deer do
today.

As for the super long neck and relatively tiny head of
herbivorous dinosaurs, Young said, “There have been numerous
hypotheses put forward to explain the evolution of extremely long
necks in sauropods, ranging from sexual selection (females
preferring longer necked males) to feeding on tall trees.”

“One possibility for the very small head-to-body ratio in
sauropods is diet,” he added. “Living herbivores that mainly eat
leaves have an extensive and enlarged digestive system, which
could help explain why sauropods had such large bodies. One
hypothesis put forward for their small heads is due to their lack
of extensive chewing. Instead, sauropods like Diplodocus would
have simply stripped leaves of branches and swallowed them
whole.”

The study sheds light on how the heads of all animals, including
those of humans, evolved.

The findings reveal that skull shape is not just influenced by
resisting the bite forces produced during jaw closure, but also
food procurement. In the case of Diplodocus, this was branch
stripping.

Young concluded, “Sauropod dinosaurs, like Diplodocus, were so
weird and different from living animals that there is no animal
we can compare them with. This makes understanding their feeding
ecology very difficult. That’s why biomechanical modeling is so
important to our understanding of long-extinct animals.”